摘要
旋喷锚杆锚固体直径是影响锚杆抗拔力和可靠性的关键。基于高压旋喷破土扩孔的物理过程,提出一种便于实际应用的高压旋喷锚杆锚固体直径计算方法,并以三门核电站二期泵房32 m深基坑支护为背景,设计现场试验验证计算方法的实用性,通过将12根试验锚杆中的3根挖出,分析旋喷参数对锚固体直径的影响。结果表明:1受土体未被完全破碎和大颗粒土沉淀等因素的影响,旋喷锚杆锚固体直径的计算值比实测数据略小,喷射压力越小,钻进速度越快,计算值和实测数据之间的偏差越大;2钻杆螺旋运动和振动导致旋喷锚杆锚固体的形状近似为椭圆形,且表面有片状毛刺,喷射压力越大,钻进速度越快,锚固体的形状越不规则;3相同条件下,增大喷嘴直径和采用二次扩孔能够获得更好的成孔质量,为提高成孔工效,并防止出现射流剖面间断,应合理配置钻进速度。
The anchorage body diameter is the key factor of the pullout resistance and the reliability of jet grouting anchor. Based on the physical process of jet grouting breaking soil, a convenient calculation method for anchorage body diameter for application is proposed. For the support of 32 m deep-foundation pit in Sanmen Nuclear Power Station, in situ tests are designed to validate the proposed method by comparing 3 excavated anchors of the 12 test anchors. The effect of jet parameters on the anchorage body diameter is also analyzed. The results reveal that under the influences of incomplete breadage and large particle sedimentation of soil, the calculated diameters are smaller than the test data, and the difference between them is larger when the jet pressure is lower and the drilling speed is faster. The jet grouting anchor with flake burrs in surface is approximate to ellipse in shape because of the spiral motion and vibration of the drill pipe. The higher the jet pressure, the faster the drilling speed, leading to more irregular shape. Under the same condition, reaming quality is better by increasing the nozzle diameter and using two times of reaming. In order to improve the reaming efficiency and to avoid the appearance of discontinuous jet profile, the drilling speed should be designed in a suitable range.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2016年第10期1783-1788,共6页
Chinese Journal of Geotechnical Engineering
基金
中国水利水电科学研究院青年科研专项基金项目(1518)
关键词
旋喷锚杆
锚固体直径
影响参数
现场试验
jet-grouting anchor
anchorage body diameter
influence parameter
in situ test
